Solved: Re: BGP Routes not showing

mimarop@ · ‎02-23-2020

What could be the problem when BGP route 172.16.0.0/24 from vIOS9 is not showing multiple paths to vIOS6, vIOS4, vIOS8, while both paths to 172.16.0.0/24 is showing in vIOS2 and vIOS3. Below are the config as well.

vIOS6#sh run | sec bgp
router bgp 200
bgp router-id 6.6.6.6
bgp log-neighbor-changes
network 1.1.1.0 mask 255.255.255.252
network 3.3.3.0 mask 255.255.255.252
network 20.20.20.0 mask 255.255.255.252
network 172.17.0.0 mask 255.255.255.0
neighbor 1.1.1.1 remote-as 100
neighbor 3.3.3.2 remote-as 300
neighbor 20.20.20.2 remote-as 200
neighbor 20.20.20.2 next-hop-self

vIOS9#sh run | sec bgp
router bgp 100
bgp router-id 2.2.2.2
bgp log-neighbor-changes
network 1.1.1.0 mask 255.255.255.252
network 2.2.2.0 mask 255.255.255.252
network 172.16.0.0 mask 255.255.255.0
neighbor 1.1.1.2 remote-as 200
neighbor 2.2.2.2 remote-as 400

vIOS1#sh run | sec bgp
router bgp 400
bgp router-id 8.8.8.8
bgp log-neighbor-changes
network 2.2.2.0 mask 255.255.255.252
network 40.40.40.0 mask 255.255.255.252
network 50.50.50.0 mask 255.255.255.252
neighbor 2.2.2.1 remote-as 100
neighbor 40.40.40.1 remote-as 400
neighbor 40.40.40.1 next-hop-self
neighbor 50.50.50.2 remote-as 400
neighbor 50.50.50.2 next-hop-self

vIOS4#sh run | sec bgp
router bgp 400
bgp router-id 7.7.7.7
bgp log-neighbor-changes
network 4.4.4.0 mask 255.255.255.252
network 5.5.5.0 mask 255.255.255.252
network 60.60.60.0 mask 255.255.255.252
network 70.70.70.0 mask 255.255.255.252
network 192.168.30.0
neighbor 60.60.60.1 remote-as 400
neighbor 60.60.60.1 next-hop-self
neighbor 70.70.70.1 remote-as 400
neighbor 70.70.70.1 next-hop-self
neighbor 192.168.10.1 remote-as 300
neighbor 192.168.10.1 ebgp-multihop 2
neighbor 192.168.10.1 update-source Loopback20

vIOS8#sh run | sec bgp
router bgp 300
bgp router-id 11.11.11.11
bgp log-neighbor-changes
network 3.3.3.0 mask 255.255.255.252
network 4.4.4.0 mask 255.255.255.252
network 5.5.5.0 mask 255.255.255.252
network 30.30.30.0 mask 255.255.255.252
network 172.18.0.0 mask 255.255.255.0
network 192.168.10.0
neighbor 3.3.3.1 remote-as 200
neighbor 30.30.30.2 remote-as 300
neighbor 30.30.30.2 next-hop-self
neighbor 192.168.30.1 remote-as 400
neighbor 192.168.30.1 ebgp-multihop 2
neighbor 192.168.30.1 update-source Loopback20

vIOS6#sh ip bgp
BGP table version is 24, local router ID is 6.6.6.6
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

Network Next Hop Metric LocPrf Weight Path
* 1.1.1.0/30 1.1.1.1 0 0 100 i
*> 0.0.0.0 0 32768 i
*> 2.2.2.0/30 1.1.1.1 0 0 100 i
* 3.3.3.0/30 3.3.3.2 0 0 300 i
*> 0.0.0.0 0 32768 i
*> 4.4.4.0/30 3.3.3.2 0 0 300 i
*> 5.5.5.0/30 3.3.3.2 0 0 300 i
* i 20.20.20.0/30 20.20.20.2 0 100 0 i
*> 0.0.0.0 0 32768 i
*> 30.30.30.0/30 3.3.3.2 0 0 300 i
* 40.40.40.0/30 1.1.1.1 0 100 400 i
*> 3.3.3.2 0 300 400 i
* 50.50.50.0/30 1.1.1.1 0 100 400 i
*> 3.3.3.2 0 300 400 i
* 60.60.60.0/30 1.1.1.1 0 100 400 i
Network Next Hop Metric LocPrf Weight Path
*> 3.3.3.2 0 300 400 i
* 70.70.70.0/30 1.1.1.1 0 100 400 i
*> 3.3.3.2 0 300 400 i
*> 172.16.0.0/24 1.1.1.1 0 0 100 i
*> 172.17.0.0/24 0.0.0.0 0 32768 i
*> 172.18.0.0/24 3.3.3.2 0 0 300 i
* 172.19.0.0/24 1.1.1.1 0 100 400 i
*> 3.3.3.2 0 300 400 i
*> 192.168.10.0 3.3.3.2 0 0 300 i
*> 192.168.30.0 3.3.3.2 0 300 400 i

vIOS4#sh ip bgp
BGP table version is 24, local router ID is 7.7.7.7
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/30 192.168.10.1 0 300 200 i
*> 2.2.2.0/30 192.168.10.1 0 300 200 100 i
*> 3.3.3.0/30 192.168.10.1 0 0 300 i
* 4.4.4.0/30 192.168.10.1 0 0 300 i
*> 0.0.0.0 0 32768 i
* 5.5.5.0/30 192.168.10.1 0 0 300 i
*> 0.0.0.0 0 32768 i
*> 20.20.20.0/30 192.168.10.1 0 300 200 i
*> 30.30.30.0/30 192.168.10.1 0 0 300 i
*>i 40.40.40.0/30 60.60.60.1 0 100 0 i
*>i 50.50.50.0/30 70.70.70.1 0 100 0 i
* i 60.60.60.0/30 60.60.60.1 0 100 0 i
*> 0.0.0.0 0 32768 i
* i 70.70.70.0/30 70.70.70.1 0 100 0 i
Network Next Hop Metric LocPrf Weight Path
*> 0.0.0.0 0 32768 i
*> 172.16.0.0/24 192.168.10.1 0 300 200 100 i
*> 172.17.0.0/24 192.168.10.1 0 300 200 i
*> 172.18.0.0/24 192.168.10.1 0 0 300 i
*>i 172.19.0.0/24 60.60.60.1 0 100 0 i
*> 192.168.10.0 192.168.10.1 0 0 300 i
*> 192.168.30.0 0.0.0.0 0 32768 i

vIOS8#sh ip bgp
BGP table version is 24, local router ID is 11.11.11.11
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/30 3.3.3.1 0 0 200 i
*> 2.2.2.0/30 3.3.3.1 0 200 100 i
* 3.3.3.0/30 3.3.3.1 0 0 200 i
*> 0.0.0.0 0 32768 i
* 4.4.4.0/30 192.168.30.1 0 0 400 i
*> 0.0.0.0 0 32768 i
* 5.5.5.0/30 192.168.30.1 0 0 400 i
*> 0.0.0.0 0 32768 i
*> 20.20.20.0/30 3.3.3.1 0 0 200 i
* i 30.30.30.0/30 30.30.30.2 0 100 0 i
*> 0.0.0.0 0 32768 i
*> 40.40.40.0/30 192.168.30.1 0 400 i
*> 50.50.50.0/30 192.168.30.1 0 400 i
*> 60.60.60.0/30 192.168.30.1 0 0 400 i
Network Next Hop Metric LocPrf Weight Path
*> 70.70.70.0/30 192.168.30.1 0 0 400 i
*> 172.16.0.0/24 3.3.3.1 0 200 100 i
*> 172.17.0.0/24 3.3.3.1 0 0 200 i
*> 172.18.0.0/24 0.0.0.0 0 32768 i
*> 172.19.0.0/24 192.168.30.1 0 400 i
*> 192.168.10.0 0.0.0.0 0 32768 i
*> 192.168.30.0 192.168.30.1 0 0 400 i

vIOS2#sh ip bgp
BGP table version is 21, local router ID is 9.9.9.9
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

Network Next Hop Metric LocPrf Weight Path
* i 1.1.1.0/30 60.60.60.2 0 100 0 300 200 i
*>i 40.40.40.2 0 100 0 100 i
* i 2.2.2.0/30 60.60.60.2 0 100 0 300 200 100 i
*>i 40.40.40.2 0 100 0 i
* i 3.3.3.0/30 40.40.40.2 0 100 0 100 200 i
*>i 60.60.60.2 0 100 0 300 i
* i 4.4.4.0/30 40.40.40.2 0 100 0 100 200 300 i
*>i 60.60.60.2 0 100 0 i
* i 5.5.5.0/30 40.40.40.2 0 100 0 100 200 300 i
*>i 60.60.60.2 0 100 0 i
* i 20.20.20.0/30 40.40.40.2 0 100 0 100 200 i
*>i 60.60.60.2 0 100 0 300 200 i
* i 30.30.30.0/30 40.40.40.2 0 100 0 100 200 300 i
*>i 60.60.60.2 0 100 0 300 i
Network Next Hop Metric LocPrf Weight Path
* i 40.40.40.0/30 40.40.40.2 0 100 0 i
*> 0.0.0.0 0 32768 i
*>i 50.50.50.0/30 40.40.40.2 0 100 0 i
* i 60.60.60.0/30 60.60.60.2 0 100 0 i
*> 0.0.0.0 0 32768 i
*>i 70.70.70.0/30 60.60.60.2 0 100 0 i
* i 172.16.0.0/24 60.60.60.2 0 100 0 300 200 100 i
*>i 40.40.40.2 0 100 0 100 i
* i 172.17.0.0/24 40.40.40.2 0 100 0 100 200 i
*>i 60.60.60.2 0 100 0 300 200 i
* i 172.18.0.0/24 40.40.40.2 0 100 0 100 200 300 i
*>i 60.60.60.2 0 100 0 300 i
*> 172.19.0.0/24 0.0.0.0 0 32768 i
* i 192.168.10.0 40.40.40.2 0 100 0 100 200 300 i
*>i 60.60.60.2 0 100 0 300 i
*>i 192.168.30.0 60.60.60.2 0 100 0 i

Jon Marshall · ‎02-24-2020

It is happening because vIOS2 and vIOS3 are receiving an IBGP route for 172.16.0.0/24 route from vIOS1 and so they cannot advertise that route to vIOS4 which is an IBGP peer.

Which means vIOS4 only gets a route advertisement from vIOS8 for that subnet.

Jon

View solution in original post

Jon Marshall · ‎02-24-2020

vIOS1 receives an EBGP route for 172.16.0.0/24 and advertises it via IBGP to vIOS2 and vIOS3.

vIOS2 and vIOS3 cannot then advertise that route to vIOS because of the IBGP rule ie. a route received from an IBGP peer cannot be advertised to another IBGP peer.

Jon

View solution in original post

Jon Marshall · ‎02-24-2020

It is happening because vIOS2 and vIOS3 are receiving an IBGP route for 172.16.0.0/24 route from vIOS1 and so they cannot advertise that route to vIOS4 which is an IBGP peer.

Which means vIOS4 only gets a route advertisement from vIOS8 for that subnet.

Jon

mimarop@ · ‎02-24-2020

Thank you for the reply.

However as you can see two paths going to 172.16.0.0/24 has been advertised to vIOS2 and vIOS3 the other path is thru vIOS4 as the eBGP peer. Why are the 2 paths not being learned in vIOS4 while learned in vIOS2 and vIOS3.

Thank you.

Jon Marshall · ‎02-24-2020

vIOS1 receives an EBGP route for 172.16.0.0/24 and advertises it via IBGP to vIOS2 and vIOS3.

vIOS2 and vIOS3 cannot then advertise that route to vIOS because of the IBGP rule ie. a route received from an IBGP peer cannot be advertised to another IBGP peer.

Jon

mimarop@ · ‎02-24-2020

Appreciate your help Jon, routes are now being learned from diff paths after configuring route-reflector.

* i 172.16.0.0/24 50.50.50.1 0 100 0 100 i
*>i 40.40.40.2 0 100 0 100 i
* 192.168.10.1 0 300 200 100 i

Thanks for your help!